Fertilizer



Feb. 19, 19416 s D, ooc 2,395,219

FERTILI ZER Filed Aug. 29,1944

ANDS 'ro' BOWL Omssmm WASTE NODULES COQLER STORAGE INVENTOR:

STAPLETON D. Gooc'H,

ATTQRNEY "900 F. as closely as that temperature can be is here involved. As the fractionation above deproceeds, including particularly fine grinding of 30% solids and 70% water. After filtering this the heat treated material, and the combination slurry, the cake has about 63% solids and about Patented Feb. 19, 1946 l l I FERTILIZER Stapleton D. Gooch, Lake Wales, Fla., assignor to Pembroke Chemical Corporation, Pembroke,

a., a corporation of Florida Application August 29, 1944, Serial No. 551,659

3 Claims. .(ei. til-4t) This invention relates to the rendering availvarious treatment stations or stages of my invenable as plant food, of P205 constituents of impure tion. This shows the best embodiment of my inphosphate of alumina clays variously known as vention at present known to me but obviously Pembroke clay, Bartow clay, road clay phosphatic changes of specific apparatus, and possibly the overburden, and the like, which abound particusequence thereof can be changed without departlarly in the phosphate district in Florida, and ing from the spirit of the invention as defined in possibly in other phosphate fields. These clays the appended claims. are found in Florida as overburden lying Just The raw clay is taken from its deposit by any over the pebble phosphate deposits. There are usual means and washed by any suitable appamillions of tons of this material but no comratussuch as a scrubber, log washer, or the like. mercial use has been made of it to treat'the If it has too large lumps, they can be screened P205 content thereof. Instead, this type of clay out and even ground if desired. The raw mahas only been used for road-building, foundation terial is supplied to a fractionating device such as and similar purposes. Therefore, it is an object a bowl classifier wherein the material is in susof this invention to devise a method and means pension and from which heavier settleable solids for so treating such natural impure phosphate of are emerged as sands going'to waste, while the alumina that a major portion of its normally uniiner and lighter fioatable and especially fiocavailable P205 is rendered available for thus proculent solids remaining in suspension are overducing from such clay, a commercially valuable flowed from the bowl and are passed to a thickfertilizer. The word available" as used herein ener. The thickener is provided with a water means soluble in neutral ammonium citrate by overflow and an underflow discharge from whence the standard method of the U. S. Department of issues a slurry of thickened fiocculent material Agriculture, for the determination of available that is supplied to a dewatering device such as a P205 in fertilizers. filter. Water passes from the filter by one path Another object of this invention is to discern and dewatered cake by another. The cake is then and use those factors which contribute to the supplied to a kiln wherein heat treatment of the yielding from such material, the greatest propormaterial takes place and such heat treated mation'ni' available P205. A further object is to yield terial issues from the kiln in the formoi' nodules such a fertilizer. that is substantially non-acid which are cooled in any suitable cooling device. and non-basic, and a still further object is to From the cooler, the material goes to a ball or separate from such material, quantities of those other grinding mill where it is fine ground, and other constituents thereof that are inert solids then the ground material is passed to storage suchassand, iron, etc. where it comprises the end product of this in- The invention is based upon my discovery that vention. Itis conceivable that a solid bowl centhe normally unavailable P205 of such clays can trifuge be substituted for the thickener and the be rendered available by heat treating such mafilter. terial for a sufficient period of time and at a high Clay of the type that abounds in Florida, and enough temperature so that the pH of the maespecially Pembroke clay, contains naturally from terial is maintained in a range of not substan- 15% to 30% of fiocculent material and about 70% tially less than 6.5 nor' more than 7.5 with the to 85% sand grains or grit. The sand and grit is optimum being as near 7.0 as is feasible comto be discarded to the extent that there is no mercially, and by heating to a temperature in a major portion thereof in the end product of this range of not substantially less than 700 F. nor invention since it is the fractionated fiocculent more than 1100 F., with the optimum being about material that contains the P205 whose treatment UNITED STATES PATENT OFFICE maintained. Other features of the invention have scribed takes place with the material in suspenimportance as will appear as this specification sion, the fiocculent fraction is thickened to about of apparatus for carrying out the treatment as 37% water. If centrifuged, the cake has about well as preparatory steps. 67% solids and about 33% water, but the cake The invention has been illustrated diagramshould have a solids content of not substantially matically in the accompanying drawing which less than when fed tothe kiln for economical comprises a flow-chart on which is indicated symreasons. I

bolically the various apparatus useable in the u The average content of P210: in raw Pembroke clay runs around 5%, whereas in the slurry or cake or ilocculent material prepared therefrom, that content runs around five times as much. There seems to be little or no loss of P205 content during the heat treatment whose purpose is to increase the proportion of available P205 as compared with the unavailable portion. In the cake passing to the kiln, the available P205 normally runs from 1% to 3%, whereas when it issues from the kiln and is fine ground the available P205 runs as high as 85% or the total P205 present. Examples of cake so prepared from Pembroke 'clay and passing to the kiln showed the following analyses, ignoring small amounts of manganese,

All samples showed a considerable amount of combined water. The insoluble residue was insoluble in aqua regia. The ignited residue from acid digestion showed approximately 50% Si02 volatilized with HF and 50% oxides of the Aland Fe-group with no Ca0 or MgO.

Treatment of such material by this invention rendered available from 70% to 85.5% of the P205. The presence of a. fluorine bearing constituent seems to have some effect on the highest temperatures to be used in the heat treatment or the clay, because when sucl. fluorine starts to come of! (about when the temperature reaches 1100 F), the amount of available P205 commences to drop. This may be a coincidence, but, at any rate, that temperature seems to be a critical upper limit. The temperature to which the material is heated seems to have an effect of pH. At around 700 F. pH is less than 7.0, while as the temperature rises pH goes to more than 7.0. Above 1100 F. the pH rises above 7.5, so that is another reason why 1100 F. is a critical upper chromium and titanium:

I II III Per cent Per cent Per can! AlaOI 20. 40 32. 30 27. 50 P205 23.08 27. 60 29. 00 C80--. 7.88 8. 70 9. 70 F6 0; 2. 88 4. l8 4. 90 Fluorine compound- 0. 77 0. 98 1. 50 Insoluble residue 23. 27 13. 63 ll. 00

limit. Below 700 F. the pH rises to 7.5 or above, while at 700 F. it drops appreciably, At 600' F. the available P20: drops below 38%, whereas at 700 F. the available P205 rises above 77%, so 700 F. is thus a critical lower limit.

The duration ofthe heat treatment is also important as it should not be substantially less than one hour, although a longer time seems to have no adverse effect. Fine grinding of the nodulized material after it comes from the heat treatment and is cooled, likewise has an -eflect on the percentage or the P205 made available; for instance,

taking material from the same batch, fine grind- 7 (Bureau of Standing to minus 100 screen mesh ards) gave 73 plus per cent, while grinding to minus 200 mesh gave better than available This invention, therefore, teaches how to make from what was formerly considered a worthless material, a new product that, being a neutral plant food high in available P205, should occupy a most important place in agriculture.

I claim:

1. The process of treating phosphate of alumina clay, which comprises treating such clay as it comes from its source to physically remove inert impurities therefrom, heat treating such physically purified material for a sumcient period of time at a temperature lying in a range of from 700 F. to 1100 F. as a. result of which the pH of the treated material lies in a range of from 6.5 to 7.5, cooling the heat treated material, and fine grinding the cooled material, whereby the available P205 is significantly increased over that of the raw material.

2. A new article of commerce comprising impure phosphate of alumina clay heat treated to a, temperature lying in a range of from 700 F, to 1100 F., wherein the pH thereof lies in a range of from 6.5 to 7.5 and the available P205 content thereof has been increased a significant amount.

3. The article according to claim 2, wherein the P205 content has been raised to more than double what it was in the raw state.

STAPLETON b. GOOCH. 

